Mouse amylase is an ideal model system for the analysis of mammalian genetic regulation, since the expression of its structural gene is regulated during development and is limited to a few differentiated tissues. It is also favorable system for analysis because several genetic variants with altered quantitative and qualitative expression of the amylase gene have been identified among inbred strains of mice. We have prepared doublestranded amylase cDNA which is being cloned in the plasmid pBR322. Cloned amylase cDNA will be used to measure the degree of reiteration of the amylase structural gene in genomic DNA from various strains. We will also investigate the tissue-specificity of amylase transcription by determining the concentration of amylase sequences in RNA isolated from various adult organs. The amino acid sequence variation among amylase isozymes is under investigation. Changes in gene-organization will be studied by extensive restriction-mapping of genomic DNA isolated from germ cells, developing embryos, adult organs which synthesize amylase, and adult organs in which the amylase gene is not expressed. We will also examine the tissue distribution, subcellular localization, and strain variation of non-amylase mRNAs isolated from the parotid gland. Inter-strain variation in restriction patterns will be mapped to particular chromosomes, in order to provide new linkage-markers for the mouse genome.